The organic extract of the leaves and stems of Ancistrocladus sp. was found active in the NCI AIDS-antiviral assay. Bioassay-directed separations using centrifugal countercurrent chromatography followed by HPLC on an amino-bonded phase column resulted in the identification of a novel dimeric alkaloid. In addition to the active alkaloid, several related but inactive compounds were identified. Structure elucidation and modeling studies are nearing completion; preparative isolation methods are being developed to provide additional material for biological studies.